From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 768BF3858D39 for ; Mon, 24 Jan 2022 14:31:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 768BF3858D39 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-488-ZcS0om30N5W2AK4uYTixpg-1; Mon, 24 Jan 2022 09:31:41 -0500 X-MC-Unique: ZcS0om30N5W2AK4uYTixpg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C70F351081; Mon, 24 Jan 2022 14:31:40 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1BC167E2C6; Mon, 24 Jan 2022 14:31:39 +0000 (UTC) From: Florian Weimer To: "H.J. Lu" Cc: GNU C Library Subject: Re: [PATCH] Fix glibc 2.34 ABI omission (missing GLIBC_2.34 in dynamic loader) References: <87h7bjmnt0.fsf@oldenburg.str.redhat.com> Date: Mon, 24 Jan 2022 15:31:38 +0100 In-Reply-To: (H. J. Lu's message of "Sat, 22 Jan 2022 08:08:25 -0800") Message-ID: <87k0ep2oj9.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.2 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Jan 2022 14:31:51 -0000 * H. J. Lu: > This is purely a placeholder symbol. Can you put in > a .S file with an empty text symbol: > > .text > .glob __rtld_version_placeholder_1 > __rtld_version_placeholder_1: > > __rtld_version_placeholder_1 won't take any space in > memory. We discussed this a bit on the call today. I'm worried that this way, we'd add an alias to random symbol, confusing dladdr and debuggers. H.J. suggested use a .rodata symbol instead. I think that's feasible. In the long term, we can get rid of the placeholder symbols if BFD ld doesn't generate VER_FLG_WEAK for empty symbol versions: Support creating empty ELF symbol versions without VER_FLG_WEAK Thanks, Florian